Chapter 2 Forest Cover
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CHAPTER 2 FOREST COVER 2.01 Introduction Assessment of forest cover using satellite data on a two-year cycle has been one of the most important activities of FSI since 1986. The present assessment is the 9th assessment in this series. Forest cover is defined as an area more than 1 ha in extent and having tree canopy density of 10 percent and above. This definition is based on the resolution of digital satellite data (pixel size 23.5m x 23.5m), scale of interpretation (1:50,000) and the technique employed for image processing. No distinction with respect to the type of tree crops (natural or man made) or tree species has been attempted since robust techniques are not available for making such distinction. Moreover, no cognizance of the type of land ownership or land use or legal status of land was taken as geo- referenced maps depicting such information was neither available nor possible to collect at country level. Thus, all species of trees (including bamboos, fruits or palms, etc.) and all types of lands (forest, private, community or institutional) satisfying the basic criteria of canopy density of more than 10 percent have been delineated as forest cover while interpreting satellite data. The minimum area of 1 ha for forest cover has been kept because this is the smallest area that can be delineated on a map at 1:50,000 scale. 2.02 Satellite Data and its Period The present assessment is based on digital interpretation of satellite data for the entire country. The satellite data was procured from the National Remote Sensing Agency (NRSA), Hyderabad in digital form. For the present assessment, LISS-III sensor data of IRS-1D satellite with a resolution of 23.5 m has been used. Data for nearly all the states pertained to the period from October to December 2002. These are the months when cloud cover is low and the deciduous trees still have leaves to provide satisfactory reflectance for the satellite sensors. It may be mentioned here that one scene of LISS III covers an area of about 20,000 km2 (140 km x 140 km). Due to considerable overlap (15 to 20 percent) among adjacent scenes, as many as 391 scenes are required to envelope the entire country. Also, at the border of the country or for islands, the whole scene has to be procured though area of interest may be very small part of the scene. While procuring data, only those scenes were selected where cloud cover was less than 10 percent. 2.03 Methodology Using Digital Image Processing (DIP) software, digital data from satellite available on CDs is downloaded on the Workstation. Radiometric and contrast corrections were applied for removing radiometric defects and for improving visual impact of the False Colour Composites (FCC). Geometric rectification of the data was carried out with the help of scanned SOI toposheets. Based on tone and texture the forest cover areas were delineated. Interpretation of forest cover for the whole country was done at 1:50,000 scale using polyconic projection. Normalized Difference Vegetation Index (NDVI) transformation was also used for density classification of forest cover. Areas of less than one hectare, whether classified as forest within non-forest areas or blanks within forested areas, were excluded by clustering pixels and merged with the surrounding class. The methodology has been shown schematically in Figure 2.01. Figure 2.01 Flow Chart Showing Methodology of Forest Cover Mapping The following categories of land use were delineated based on canopy density: Forest cover Crown density range Very Dense Forest (VDF) > 70 percent Moderately Dense Forest (MDF) 40-70 percent Open Forest (OF) 10-40 percent Non-forest cover Scrub <10 percent Non-forest - Water bodies - Very Dense Forest Moderately Dense Forest Open Forest Mangroves Fig. 2.02 Pictorial illustration of different classes of forests Highly degraded forest or wastelands with stumped trees having canopy density less than 10 percent were classified as scrubs, a category of non-forest cover. Shadow areas in the scenes were treated separately. Density in shadow area was either based on ground information or was assigned according to the nearest neighbour class of density. Mangrove cover was also delineated due to their unique signature along the coastal areas. Mangroves were further classified into three density classes of forest cover described above. After delineation, mangrove cover was added up with forest cover in the respective density classes. This was then followed by extensive ground verification and all the necessary corrections were subsequently incorporated. Sheet wise mosaic of districts and States/UTs was made using SOI and Census data to compute district wise and State/UT wise forest cover. 2.04 Limitations of Remote Sensing Technology However, there are still certain limitations with remote sensing technology when used for assessment of forest cover. Some of the major ones are listed below: • Since resolution of data from LISS-III is 23.5 m, the linear strips of forest cover along roads, canals, bunds and rails of width less than the resolution are generally not captured. • Young plantations and species having less chlorophyll contents in their crown do not give proper reflectance and as a result are difficult to be interpreted correctly. • Considerable details on ground may be obscured in areas having clouds and shadows. It is difficult to interpret such areas without the help of collateral data. • Variation in spectral reflectance during leafless period poses problem in interpretation. • Gregarious occurrence of bushy vegetation and certain agricultural crops, such as lantana, sugarcane, cotton, etc., often pose problems in delineation of forest cover, as their reflectance is similar to that of tree canopy. 2.05 Forest Cover: 2003 Assessment Results of present assessment (2003) of forest cover in the country are summarized in a pie chart in Figure 2.01 and Table 2.01. Forest cover is shown in three density classes viz., very dense forest (VDF) with more than 70% canopy density, moderately dense forests (MDF) with canopy density between 40% and 70% and open forests (OF) with canopy density between 10% and 40%. Scrub and water bodies are also delineated. As mentioned earlier, area under VDF, MDF and OF also includes mangrove cover of the corresponding density class. The total forest cover of the country as per 2003 assessment is 678,333 km² and this constitutes 20.64 percent of the geographic area of the country. Of this, 51,285 km² (1.56 percent) is very dense forest, 339,279 km² (10.32 percent) is moderately dense forest while 287,769 km² (8.76 percent) is open forest cover. The non-forest cover includes scrub and is estimated to cover an area of 40,269 km². Table 2.01 Status of Forest Cover in India Class Area (km²) Percent of Geographic Area Forest Cover a) VDF 51,285 1.56 b) MDF 339,279 10.32 c) Open 287,769 8.76 Total Forest Cover* 678,333 20.64 Non-forest Cover Scrub 40,269 1.23 Non-forest** 2,568,661 78.13 Total Geographic Area 3,287,263 100.00 * Including 4,461 km2 under mangroves (0.14% of country’s geographic area) ** Excludes scrubs and includes water bodies Forest Cover Assessment 2003 1.23% 1.56% 10.32% VDF 8.76% MDF Total Forest Cover = 20.64% Open Non-forest Scrub 78.13% Figure 2.03: Forest Cover Forest Cover 90000 80000 70000 60000 Open 50000 Moderately Dense Very Dense 40000 30000 (Area in '000 sq.km.) 20000 10000 0 Goa Goa Bihar Bihar Delhi Orissa Kerala Assam Punjab Punjab Sikkim Sikkim Gujarat Tripura Tripura Haryana Manipur Manipur Mizoram Jharkhand Nagaland Nagaland Rajasthan Rajasthan Karnataka Tamilnadu Meghalaya Meghalaya Chandigarh Chandigarh Uttaranchal Uttaranchal West Bengal Bengal West Pondicherry Maharashtra Chhattisgarh Lakshdweep Uttar Pradesh Daman & Diu & Daman Andhra Pradesh Madhya Pradesh Himachal Pradesh Jammu & Kashmir Arunachal Pradesh Andaman & Nicobar Andaman & Dadar Nagar Haveli Figure 2.04: Forest Cover in States and UTs 2.06 State/UT wise Forest Cover The State/UT wise forest cover in the country is shown in Table 2.02 and as bar chart in Figure 2.03. It shows that Madhya Pradesh with 76,429 km² has the maximum area under forest cover, followed by Arunachal Pradesh (68,019 km²) and Chhattisgarh (55,998 km²). Considering proportion of geographic area under forest cover, Mizoram has the maximum percentage (87.42 percent). It is followed by Andaman & Nicobar Islands (84.42 percent), Nagaland (82.09percent) and Arunachal Pradesh (81.22 percent). Table 2.02 Forest cover in States/UTs in India (Area in km²) State/UT Geographic Forest Cover Percent Scrub Area VDF MDF OF Total Andhra Pradesh 275,069 23 24,356 20,040 44,419 16.15 9,748 Arunachal Pradesh 83,743 13,907 39,604 14,508 68,019 81.22 116 Assam 78,438 1,684 11,358 14,784 27,826 35.48 219 Bihar 94,163 76 2,951 2,531 5,558 5.90 150 Chhattisgarh 135,191 1,540 37,440 17,018 55,998 41.42 88 Delhi 1,483 0 52 118 170 11.47 1 Goa 3,702 0 1,255 901 2,156 58.24 0 Gujarat 196,022 114 6,231 8,601 14,946 7.62 1,743 Haryana 44,212 2 518 997 1,517 3.43 68 Himachal Pradesh 55,673 1,093 7,883 5,377 14,353 25.78 389 Jammu & Kashmir 222,236 2,102 8,395 10,770 21,267 9.57 2,947 Jharkhand 79,714 2,544 9,137 11,035 22,716 28.50 807 Karnataka 191,791 431 22,030 13,988 36,449 19.00 3,141 Kerala 38,863 334 9,294 5,949 15,577 40.08 72 Madhya Pradesh 308,245 4,000 37,843 34,586 76,429 24.79 2,378 Maharashtra 307,713 8,070 20,317 18,478 46,865 15.23 4,175 Manipur 22,327 720 5,818 10,681 17,219 77.12 74 Meghalaya 22,429 168 6,323 10,348 16,839 75.08 169 Mizoram 21,081 84 7,404 10,942 18,430 87.42